Assessments of inflammation in 12-week WT and PAI-1^−/− hearts. An elevated inflammatory response, indicated by iNOS (A), iCAM (B), and KC (C) mRNA levels, was observed in 12-week PAI-1^−/− hearts. Compared with WT heart (D), CD45 staining revealed enhanced local leukocyte infiltration in cardiac tissue of 12-week-old PAI-1^−/− mice (E). Leukocyte infiltration and recruitment after peritoneal stimulation with thioglycollate were significantly enhanced in PAI-1^−/− mice compared with WT mice (F). Comparison of peritoneal leukocyte viabilities indicated that the differences in leukocyte infiltration were not due to different rates of cell death (G). n ≥ 5 for each age group; *P < .05.